A previous Generalized Anxiety Disorder Impact Survey (GADIS I) performed on 15,399 Belgian patients consulting their primary care physicians, revealed high prevalences of generalized anxiety disorder (GAD) and major depression (MD) with important regional differences. The objective of this study (GADIS II) was to replicate previous findings and to evaluate the role of socioeconomic factors in the diagnoses of GAD and MD. A large-scale cross-sectional survey was conducted in a random sample of 377 general practitioners distributed geographically over Belgium and Luxemburg. Each physician was asked to screen 40 consecutive patients at predefined time periods for the presence of GAD and MD using sections of the Mini International Neuropsychiatric Interview (MINI). Socioeconomic parameters were collected. The level of impairment was assessed using the Sheehan Disability Scale. In a sample of 13,699 patients, point prevalences of GAD and of MD were found to be 13.4 and 11.0%, respectively. Overall, 17.8% of the population was positive for GAD and/or MD. Both disorders were significantly more frequent in women than in men. Marked regional differences were observed with prevalences for GAD and/or MD of 24.2% in Brussels, 22.7% in Wallonia, 13.6% in Luxemburg and 12.9% in Flanders. Several socioeconomic factors were significantly associated with positive diagnoses: living alone, a low level of education and unemployment. However, regional differences remained significant even after controlling for socioeconomic factors. The study confirms the high prevalence of GAD and MD in primary care and the role of several socioeconomic and regional factors in the illnesses. Depression and Anxiety 25:506-513, 2008.